rac-[ethylenebis(2-(thexyldimethylsiloxy)indenyl)]zirconium dichloride: synthesis, molecular structure and olefin polymerization catalysis

: Leino R, Luttikhedde HJG, Lehmus P, Wilen CE, Sjoholm R, Lehtonen A, Seppala JV, Nasman JH

Publisher: ELSEVIER SCIENCE SA

: 1998

Journal of Organometallic Chemistry

JOURNAL OF ORGANOMETALLIC CHEMISTRY

: J ORGANOMET CHEM

: 559

: 1-2

: 65

: 72

: 8

: 0022-328X

DOI: https://doi.org/10.1016/S0022-328X(98)00405-7

The synthesis and molecular structure of rac-[ethylenebis(2-(thexyldimethylsiloxy)indenyl)]zirconium dichloride (4), is reported. In combination with methylaluminoxane (MAO), 4 forms an active catalyst system for homogeneous polymerization of ethylene and propylene. The high activity of 4/MAO is retained at low [Al]:[Zr] ratios [(150-250):1]. Decreasing polymerization temperature or the [Al]:[Zr] ratio results in production of polyethylene having a high molecular weight shoulder in its molecular weight distribution (MWD). Deconvolution of the MWDs into a series of calculated Flory-distribution curves indicates that with this catalyst system ethylene is polymerized by three different types of active sites, whereas propylene is predominantly polymerized by two active sites. Complex 4 crystallizes in the indenyl-backward conformation. The ligand backbone adopts the expected C-2 symmetry. (C) 1998 Elsevier Science S.A. All rights reserved.